Nanoimprinting method, method for producing a droplet arrangement pattern, and method for fabricating substrates

ABSTRACT

The disclosed nanoimprinting method suppresses fluctuations in thickness of residual film and defects due to residual gas in a resist film, onto which a pattern of protrusions and recesses is transferred, in a nanoimprinting method that employs the ink jet method to coat a substrate with droplets of resist material. Droplets are coated onto a substrate such that the spaces between the droplets along an A direction which is substantially parallel to the direction of the lines of a linear pattern of protrusions and recesses are longer than the spaces between the droplets in a B direction which is substantially perpendicular to the A direction, in a nanoimprinting method that coats a substrate with the droplets of a resist material using the ink jet method.

TECHNICAL FIELD

The present invention is related to a nanoimprinting method that employsa mold having a fine pattern of protrusions and recesses, andparticularly to a method that performs nanoimprinting after coating asubstrate with resist using the ink jet method. The present invention isalso related to a method for producing a droplet arrangement pattern tobe employed in the nanoimprinting method. The present invention is alsorelated to a method for fabricating substrates employing thenanoimprinting method and the method for producing a droplet arrangementpattern.

BACKGROUND ART

There are high expectations regarding utilization of pattern transfertechniques that employ a nanoimprinting method to transfer patterns ontoresist coated on objects to be processed, in applications to producemagnetic recording media such as DTM (Discrete Track Media) and BPM (BitPatterned Media) and semiconductor devices.

The nanoimprinting method is a development of the well known embossingtechnique employed to produce optical discs. In the nanoimprintingmethod, an original mold (commonly referred to as a stamper or atemplate), on which a pattern of protrusions and recesses is formed, ispressed against resist coated on an object to be processed. Pressing ofthe original onto the resist causes the resist to mechanically deform orto flow, to precisely transfer the fine pattern. If a mold is producedonce, nano level fine structures can be repeatedly molded in a simplemanner. Therefore, the nanoimprinting method is an economical transfertechnique that produces very little harmful waste and discharge.Therefore, there are high expectations with regard to application of thenanoimprinting method in various fields.

In the conventional nanoimprinting method, an object to be processed wasuniformly coated with resist by the spin coat method or the like, toform a resist film thereon. Thereafter, the surface of the mold havingthe pattern of protrusions and recesses thereon is pressed against theresist film, to perform pattern transfer. However, when pattern transferis performed in this manner, there are cases in which fluctuations occurin the thickness of a residual layer (residual resist film which is notpressed during imprint molding, and remains at positions correspondingto the protrusions of the pattern of protrusions and recesses of themold; also referred to as “residue”) of the resist film on which thepattern has been transferred. In such cases, the residual layer isgenerally removed by dry etching with settings that enable the thickestresidual layer to be removed. During such removal, problems occur, suchas the base layer underneath thin portions of the residual layer beingetched as well, and protrusion portions of the pattern which shouldremain as a mask are excessively etched, which result in the processingaccuracy of a substrate deteriorating. This is considered to be due tothe fact that the pressing force applied by the upper surfaces (thesurfaces that face the resist film during imprinting) of protrusionshaving large areas and the pressing force applied by the upper surfacesof protrusions having small areas are different. Another factor is thatthe resist is coated uniformly, although patterns of protrusions andrecesses have protrusions or recesses of difference widths by nature,and the coarse and fine recesses act as escape routes for the resistwhen the patterns are pressed against the resist.

In view of the above, Japanese PCT Publication No. 2008-502157, and U.S.Patent Application Publication Nos. 20090014917, 20090115110,20070228593, and 20090148619 disclose methods that employ the ink jetmethod to control the amount of resist to be coated at each region ofobjects to be processed, according to the pattern density (thepercentage of protrusions or recesses per unit area when a pattern ofprotrusions and recesses is viewed from above) of patterns ofprotrusions and recesses when molds are pressed against the objects tobe processed. That is, the publications listed above employ the ink jetmethod to reduce fluctuations in thickness of the residual layer, byoptimizing the positional distribution (droplet arrangement pattern) atwhich droplets of resist material are arranged on objects to beprocessed according to pattern densities.

In addition, Japanese Unexamined Patent Publication No. 2008-042187discloses a method for adjusting the amount of droplets and coatingorders, to solve the problem that evaporation times of components differdue to temporal differenced among timings at which droplets are coated.

However, the methods disclosed in the publications listed above assumethe droplets spread isotropically when the mold is pressed against thedroplets, and define the droplet arrangements such that spaces amongadjacent droplets are minimal. Therefore, problems of thicknessfluctuations in the thicknesses of residual layers and defects due toresidual gas persist, in regions of the patterns of protrusions andrecesses where patterns are formed as lines.

The present invention has been developed in view of the foregoingcircumstances. It is an object of the present invention to provide ananoimprinting method that suppresses fluctuations in thickness of aresidual layer and defects due to residual gas in a resist film, ontowhich a pattern of protrusions and recesses is transferred, in ananoimprinting method that employs the ink jet method to coat asubstrate with droplets of resist material.

It is another object of the present invention to provide a method forproducing a droplet arrangement pattern to be utilized in ananoimprinting method that employs the ink jet method to coat asubstrate with droplets of resist material that enables fluctuations inthickness of a residual layer and defects due to residual gas in aresist film, onto which a pattern of protrusions and recesses istransferred, to be suppressed.

It is still another object of the present invention to provide a methodfor fabricating substrates that enables highly accurate and high yieldfabrication of substrates, by suppressing fluctuations in thickness of aresidual layer and defects due to residual gas in a resist film, ontowhich a pattern of protrusions and recesses is transferred.

Disclosure of the Invention

A first nanoimprinting method of the present invention that achieves theabove object comprises:

-   -   coating a substrate with a plurality of droplets of resist        material by the ink jet method; and    -   pressing a linear pattern of protrusions and recesses of a mold        onto the surface of the substrate which is coated with the        droplets, to spread the droplets on the substrate, to form a        resist film constituted by bonds among the spread plurality of        droplets and to transfer the linear pattern of protrusions and        recesses onto the resist film;    -   the droplets being coated on the substrate such that the spaces        among droplets in an A direction substantially parallel to the        direction of the lines of the linear pattern of protrusions and        recesses are longer than the spaces among droplets in a B        direction substantially perpendicular to the A direction within        a line transfer region of the substrate that faces the linear        pattern of protrusions and recesses when the linear pattern of        protrusions and recesses is pressed against the substrate.

In the present specification, the expression “linear pattern ofprotrusions and recesses” refers to a pattern of protrusions andrecesses that causes anisotropy to occur in the spreading directions ofdroplets such that the shapes of the droplets approximate ellipses whenthe pattern is pressed against the droplets, due to the shape of thepattern. The most typical linear pattern of protrusions and recesses isa pattern of protrusions and recesses of the line and space time. Thelinear pattern of protrusions and recesses may be included at least at aportion of the pattern of protrusions and recesses on the surface of themold.

The expression “resist film constituted by bonds among the spreadplurality of droplets” refers to a film of resist material formed bydroplets having overlapping spaces in which they spread bonding to eachother when the droplets of resist materials are spread by being pressed.

The expression “line transfer region” refers to a region of thesubstrate that faces the linear pattern of protrusions and recesses whenthe linear pattern of protrusions and recesses is pressed against thesubstrate.

The expression “direction of the lines of the linear pattern ofprotrusions and recesses” refers to a direction in which spreading ofthe droplets is facilitated, from along the directions along the patternformation surface of the mold.

The expression “an A direction substantially parallel to the directionof the lines” includes directions, which are practically equal to thedirection of the lines of the linear pattern of protrusions andrecesses, within a range that enables obtainment of the operativeeffects of the present invention, in addition to the direction of thelines of the linear pattern of protrusions and recesses.

The expression “a direction substantially perpendicular to the Adirection” includes directions, which are practically equal to thedirection perpendicular to the A direction, within a range that enablesthe operative effects of the present invention to be obtained, inaddition to the direction perpendicular to the A direction.

The expressions “spaces among droplets in an A direction” and “spacesamong droplets in a B direction” refers to the distance in the Adirection and in the B direction between a droplet and another dropletarranged remote from the droplet along the A direction or along the Bdirection. In the case that there are a plurality of other droplets, thespace refers to a distance to the immediately adjacent droplet.

Further, in the first nanoimprinting method of the present invention, itis preferable for a ratio Wa/Wb between an average space Wa betweendroplets in the A direction and an average space Wb between droplets inthe B direction to satisfy the following formula (1)

1.8≦Wa/Wb≦0.52V ^(1/3) /d   (1)

In the present specification, V represents the average volume of eachcoated droplet, and d represents a target average thickness of theresist film (including the residual layer), onto which the pattern ofprotrusions and recesses is transferred following the spreading of thedroplets.

In the present specification, the expression “average space betweendroplets” refers to a value obtained by measuring the space between thecentral coordinates of a plurality of droplets arranged on the substratewithin the line transfer region at at least two locations. In the casethat the linear pattern of protrusions and recesses changesdiscontinuously, the line transfer region may be divided into regions inwhich the linear pattern of protrusions and recesses is continuous, andthe average space between droplets may be calculated for each dividedregion. Differences occur between set values and actual values of spacesamong droplets in the ink jet method, due to discharge performance ofink jet heads, compatibility between the properties of liquids and thesurfaces of substrates, conditions (such as temperature) of theenvironment in which ink jet apparatuses are utilized, and the accuracyof XY scanning systems during ink jet drawing. Accordingly, there is apossibility that differences from settings set in the system of an inkjet printer will occur in the spaces among droplets in the A directionand in the B direction, when arranging droplets on substrates by the inkjet method. Therefore, it is necessary to actually measure and adjustthe spaces between the central coordinates of a plurality of droplets.

In the first nanoimprinting method of the present invention, it ispreferable for the resolution in the A direction which is defined by anink jet head that performs the coating with the droplets to be set lowerthan the resolution in the B direction which is defined by the ink jethead.

In the first nanoimprinting method of the present invention, it ispreferable for:

-   -   one of the A direction and the B direction to be set as a main        scanning direction in the ink jet method, and the other to be        set as a sub scanning direction in the ink jet method; and    -   the ink jet head to be set such that the intervals among lattice        points along the sub scanning direction is an integer multiple        of effective intervals among ink expelling outlets of the ink        jet head along the sub scanning direction, when coating the        droplets according to a droplet arrangement pattern constituted        by a plurality of lattice points that correspond to positions at        which each of the plurality of droplets are to be arranged.

In the present specification, the expression “intervals among latticepoints along the sub scanning direction” refers to the smallest distancein the sub scanning direction between a lattice point and anotherlattice point.

The expression “effective intervals among ink expelling outlets” refersto the smallest distance in the sub scanning direction between an inkexpelling outlet and another ink expelling outlet.

A second nanoimprinting method of the present invention comprises:

-   -   coating a substrate with a plurality of droplets of resist        material by the ink jet method; and    -   pressing a straight linear pattern of protrusions and recesses        of a mold onto the surface of the substrate which is coated with        the droplets, to spread the droplets on the substrate, to form a        resist film constituted by bonds among the spread plurality of        droplets and to transfer the straight linear pattern of        protrusions and recesses onto the resist film;    -   the droplets being coated on the substrate according to a        droplet arrangement pattern constituted by a plurality of        lattice points that correspond to positions at which each of the        plurality of droplets are to be arranged within a straight line        transfer region of the substrate that faces the straight linear        pattern of protrusions and recesses when the straight linear        pattern of protrusions and recesses is pressed against the        substrate; and    -   the droplet arrangement pattern having basic unit lattices        having periodicity in each of an A direction substantially        parallel to the direction of the lines of the straight linear        pattern of protrusions and in a B direction substantially        perpendicular to the A direction, and the periods of the        periodicity in the A direction being longer than the periods of        the periodicity in the B direction.

In the present specification, the expression “straight linear pattern ofprotrusions and recesses” refers to the aforementioned linear pattern ofprotrusions and recesses, and particularly to a pattern of protrusionsand recesses that causes the long axes of the elliptical shapes of theplurality of droplets to be oriented in a single direction when thepattern is pressed against the droplets.

The expression “straight line transfer region” refers to a region of thesubstrate that faces the straight linear pattern of protrusions andrecesses when the straight linear pattern of protrusions and recesses ispressed against the substrate.

The expression “direction of the lines of the straight linear pattern ofprotrusions and recesses” refers to the aforementioned direction of thelines, and particularly refers to a direction along the long axes of theplurality of ellipses.

The expression “a droplet arrangement pattern constituted by a pluralityof lattice points that correspond to positions at which each of theplurality of droplets are to be arranged” refers to a two dimensionalcoordinate system constituted by a group of lattice points thatrepresent the arrangement of the plurality of droplets, which functionsas a reference for droplet arrangement when arranging the droplets onthe substrate.

The expression “basic unit lattices” refers to the smallest repeatingunits of the droplet arrangement pattern, which has periodicity.

Further, it is preferable for each basic unit lattice to be a unitstructure that includes lattice points L1=0·a+0·b and L2=½·a+½·b, in thecase that an initial point for a vector a that represents a singleperiod in the A direction and an initial point for a vector b thatrepresents a single period in the B direction are set at a singlelattice point, and the basic unit lattice to be designated as aparallelogram formed by the vector a and the vector b.

In the present specification, the expression “unit structure” refers toa specific arrangement of lattice points that constitute the basic unitlattice. That is, the group of lattice points that constitute thedroplet arrangement pattern is expressed by repetitions of basic unitlattices having the unit structures.

Further, it is preferable for a ratio Ta/Tb between a length Ta of asingle period in the A direction and a length Tb of a single period inthe B direction to satisfy the following formula (2)

1.8 ≦Ta/Tb≦0.52V ^(1/3) /d   (2)

In the present specification, V represents the average volume ofdroplets corresponding to representative lattice points of the basicunit lattice, and d represents the average thickness of the resist film(including the residual layer).

In the second nanoimprinting method of the present invention, it ispreferable for the resolution in the A direction which is defined by anink jet head that performs the coating with the droplets to be set lowerthan the resolution in the B direction which is defined by the ink jethead.

In the second nanoimprinting method of the present invention, it ispreferable for one of the A direction and the B direction to be set as amain scanning direction in the ink jet method, and the other to be setas a sub scanning direction in the ink jet method; and

-   -   the ink jet head to be set such that the intervals among lattice        points along the sub scanning direction is an integer multiple        of effective intervals among ink expelling outlets of the inkjet        head along the sub scanning direction, when coating the droplets        according to a droplet arrangement pattern constituted by a        plurality of lattice points that correspond to positions at        which each of the plurality of droplets are to be arranged.

A method for producing a droplet arrangement pattern of the presentinvention, which is to be a reference for arranging droplets to beemployed in a nanoimprinting method comprising coating a first substratewith a plurality of droplets of resist material by the ink jet method,and pressing a linear pattern of protrusions and recesses of a mold ontothe surface of the first substrate which is coated with the droplets,comprises:

-   -   coating a plurality of droplets of resist material at a standard        amount onto a second substrate different from the first        substrate;    -   pressing a second mold having a pattern of protrusions and        recesses, which is the same as the linear pattern of protrusions        and recesses, against the surface of the second substrate which        is coated with the droplets, to spread the droplets to a degree        that the droplets contact each other;    -   causing the shapes of the spread droplets of the standard amount        to approximate ellipses;    -   measuring the arrangement of the ellipses;    -   rearranging the arrangements of the measured ellipses such that        the plurality of ellipses are closely packed; and    -   obtaining a droplet arrangement pattern constituted by a        plurality of lattice points that correspond to positions at        which the plurality of droplets are to be arranged, by        designating the centers of each of the rearranged plurality of        ellipses as lattice points.

In the present specification, the expression “standard amount” refers toan approximate amount of resist material within each droplet, whencoating the first substrate with the plurality of droplets of resistmaterial.

The expression “to spread the droplets to a degree that the dropletscontact each other” when pressing the second mold against the secondsubstrate refers to not pressing the second mold against the secondsubstrate completely, but stopping the pressing operation in a state inwhich the droplets contact each other, as well as to adjusting theamounts of resist material within the droplets and the dropletarrangement pattern such that the droplets contact each other afterrepetitively pressing the second mold against the second substratecompletely.

A third nanoimprinting method of the present invention comprises:

-   -   coating a substrate with a plurality of droplets of a resist        material by the ink jet method; and    -   pressing a linear pattern of protrusions and recesses of a mold        onto the surface of the substrate which is coated with the        droplets, to spread the droplets on the substrate, to form a        resist film constituted by bonds among the spread plurality of        droplets and to transfer the linear pattern of protrusions and        recesses onto the resist film;    -   the droplets being coated onto the substrate according to a        droplet arrangement pattern produced by the method for producing        a droplet arrangement pattern of the present invention.

In the third nanoimprinting method of the present invention, it ispreferable for the resolution in the direction of the long axes of theellipses which is defined by an ink jet head that performs the coatingwith the droplets to be set lower than the resolution in the directionof the short axes of the ellipses which is defined by the ink jet head.

In the third nanoimprinting method of the present invention, it ispreferable for one of the direction of the long axes and the directionof the short axes to be set as a main scanning direction in the ink jetmethod, and the other to be set as a sub scanning direction in the inkjet method; and

-   -   for the ink jet head to be set such that the intervals among        lattice points along the sub scanning direction is an integer        multiple of effective intervals among ink expelling outlets of        the ink jet head along the sub scanning direction, when coating        the droplets according to a droplet arrangement pattern        constituted by a plurality of lattice points that correspond to        positions at which each of the plurality of droplets are to be        arranged.

A method for fabricating substrates of the present invention comprises:

-   -   forming a resist film, on which a pattern of protrusions and        recesses is formed, on a substrate by a nanoimprinting method of        the present invention as described above; and    -   performing dry etching using the resist film as a mask, to form        a pattern of protrusions and recesses corresponding to the        pattern of protrusions and recesses transferred on the resist        film, to obtain a substrate having a predetermined pattern        thereon.

In the first nanoimprinting method of the present invention, thedroplets are coated on the substrate such that the spaces among dropletsin the A direction substantially parallel to the direction of the linesof the linear pattern of protrusions and recesses are longer than thespaces among droplets in the B direction substantially perpendicular tothe A direction. That is, the droplets are arranged taking the directionof the lines into consideration. Therefore, the droplets can be spreadevenly, even if anisotropy occurs in the spreading direction of thedroplets due to the pattern shape of the linear pattern of protrusionsand recesses. As a result, fluctuations in thickness of residual resistfilm, on which a pattern of protrusions and recesses has beentransferred, and defects due to residual gas, can be suppressed in ananoimprinting method that performs nanoimprinting after coating asubstrate with droplets of resist material using the ink jet method.

Further, in the second nanoimprinting method of the present invention,the droplets are coated onto the straight line transfer region of thesubstrate according to the droplet arrangement pattern. The dropletarrangement pattern has the basic unit lattices having periodicity inboth the A direction, which is substantially parallel to the directionof the lines of the linear pattern of protrusions and recesses, and theB direction, which is substantially perpendicular to the B direction.The periods of the periodicity in the A direction are longer than theperiods of the periodicity in the B direction, that is, the droplets arearranged taking the direction of the lines into consideration.Therefore, the second nanoimprinting method exhibits the sameadvantageous effects as those exhibited by the first nanoimprintingmethod of the present invention.

In the first and second nanoimprinting methods of the present invention,a configuration may be adopted, wherein: the resolution in the Adirection which is defined by an ink jet head that performs the coatingwith the droplets is set to be lower than the resolution in the Bdirection which is defined by the ink jet head. In this case, throughputduring droplet discharge can be improved, while maintaining theresolution performance of the ink jet printer as a whole.

In the first and second nanoimprinting methods of the present invention,a configuration may be adopted, wherein: one of the A direction and theB direction is set as a main scanning direction in the ink jet method,and the other is set as a sub scanning direction in the ink jet method;and the ink jet head is set such that the intervals among lattice pointsalong the sub scanning direction is an integer multiple of effectiveintervals among ink expelling outlets of the ink jet head along the subscanning direction, when coating the droplets according to a dropletarrangement pattern constituted by a plurality of lattice points thatcorrespond to positions at which each of the plurality of droplets areto be arranged. In this case, the droplets can be coated efficiently,and the throughput during droplet discharge can be improved further.

In the third nanoimprinting method of the present invention, thedroplets are coated on the substrate according to the dropletarrangement pattern which is produced by the method for producing adroplet arrangement pattern of the present invention. As a result, thedroplets are arranged taking the direction of the lines intoconsideration. Therefore, the third nanoimprinting method exhibits thesame advantageous effects as those exhibited by the first nanoimprintingmethod of the present invention.

In the third nanoimprinting method of the present invention, aconfiguration may be adopted, wherein: the resolution in the directionof the long axes of the ellipses which is defined by an ink jet headthat performs the coating with the droplets is set to be lower than theresolution in the direction of the short axes of the ellipses which isdefined by the ink jet head. In this case, throughput during dropletdischarge can be improved, while maintaining the resolution performanceof the ink jet printer as a whole.

In the third nanoimprinting method of the present invention, aconfiguration may be adopted, wherein: one of the direction of the longaxes and the direction of the short axes is set as a main scanningdirection in the ink jet method, and the other is set as a sub scanningdirection in the ink jet method; and the ink jet head is set such thatthe intervals among lattice points along the sub scanning direction isan integer multiple of effective intervals among ink expelling outletsof the ink jet head along the sub scanning direction, when coating thedroplets according to a droplet arrangement pattern constituted by aplurality of lattice points that correspond to positions at which eachof the plurality of droplets are to be arranged. In this case, thedroplets can be coated efficiently, and the throughput during dropletdischarge can be improved further.

The method for producing a droplet arrangement pattern of the presentinvention comprises the steps of: coating a plurality of droplets ofresist material at a standard amount onto a test substrate; pressing atest mold having a pattern of protrusions and recesses, which is atleast partially the same as the linear pattern of protrusions andrecesses, against the surface of the test substrate which is coated withthe droplets, to spread the droplets to a degree that the dropletscontact each other; causing the shapes of the spread droplets of thestandard amount to approximate ellipses; measuring the arrangement ofthe ellipses; rearranging the arrangements of the measured ellipses suchthat the plurality of ellipses are closely packed; and obtaining adroplet arrangement pattern constituted by a plurality of lattice pointsthat correspond to positions at which the plurality of droplets are tobe arranged, by designating the centers of each of the rearrangedplurality of ellipses as lattice points. A droplet arrangement patternthat takes the direction of the lines of the linear pattern ofprotrusions and recesses into consideration is obtained by the methodfor producing a droplet arrangement pattern of the present invention.Therefore, fluctuations in thickness of residual resist film, on which apattern of protrusions and recesses has been transferred, and defectsdue to residual gas, can be suppressed in a nanoimprinting method thatperforms nanoimprinting after coating a substrate with droplets ofresist material using the ink jet method, by utilizing the dropletarrangement pattern produced in this manner.

Further, the method for fabricating substrates performs dry etchingusing a resist film, on which a pattern has been transferred by ananoimprinting method of the present invention, as a mask. Dry etchingis performed using the mask formed in this manner, which has neitherfluctuations in the thickness of a residual layer nor defects due toresidual gas. Therefore, substrates can be produced with high accuracyand at high yields.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram that schematically illustrates the relationshipbetween the direction of lines of a linear pattern of protrusions andrecesses, and a coating arrangement for a plurality of droplets thatinclude photocuring resin, in a first imprinting method.

FIG. 2A is a diagram that schematically illustrates an example of alinear pattern of protrusions and recesses.

FIG. 2B is a diagram that schematically illustrates another example of alinear pattern of protrusions and recesses.

FIG. 2C is a diagram that schematically illustrates still anotherexample of a linear pattern of protrusions and recesses.

FIG. 2D is a diagram that schematically illustrates still yet anotherexample of a linear pattern of protrusions and recesses.

FIG. 2E is a diagram that schematically illustrates an example of apattern which is not a linear pattern of protrusions and recesses.

FIG. 3A is a diagram that schematically illustrates a mold having linearpatterns of protrusions and recesses formed thereon.

FIG. 3B is a diagram that schematically illustrates a substrate ontowhich the mold of FIG. 3A is pressed as a target of processing.

FIG. 4A is a schematic sectional diagram taken along line I-I of FIG.3A.

FIG. 4B is a schematic sectional diagram taken along line II-II of FIG.3B.

FIG. 5A is a diagram that schematically illustrates a transparentsubstrate on which droplets are uniformly arranged, in a state prior tohaving a flat plate pressed thereon.

FIG. 5B is a diagram that schematically illustrates the manner in whichdroplets, which are uniformly arranged on a transparent substrate,spread as a flat plate is pressed thereon.

FIG. 5C is a diagram that schematically illustrates a resist film,formed as a result of uniformly arranging droplets onto a transparentsubstrate and then pressing a flat plate onto the substrate.

FIG. 6A is a diagram that schematically illustrates a transparentsubstrate on which droplets are uniformly arranged, in a state prior tohaving a mold pressed thereon.

FIG. 6B is a diagram that schematically illustrates the manner in whichdroplets, which are uniformly arranged on a transparent substrate,spread as a mold is pressed thereon.

FIG. 6C is a diagram that schematically illustrates a resist film,formed as a result of uniformly arranging droplets onto a transparentsubstrate and then pressing a mold onto the substrate.

FIG. 7A is a diagram that schematically illustrates a transparentsubstrate on which droplets are arranged taking the direction of linesinto consideration, in a state prior to having a mold pressed thereon.

FIG. 7B is a diagram that schematically illustrates the manner in whichdroplets, which are arranged on a transparent substrate taking thedirection of lines into consideration, spread as a mold is pressedthereon.

FIG. 7C is a diagram that schematically illustrates a resist film,formed as a result of arranging droplets onto a transparent substratetaking the direction of lines into consideration and then pressing amold onto the substrate.

FIG. 8 is a diagram that schematically illustrates a state in whichcircles are closely packed, taking the direction of lines intoconsideration.

FIG. 9 is a diagram that schematically illustrates the manner in whichdroplets spread, when a ratio between an average space between dropletsWa in an A direction and an average space between droplets Wb in a Bdirection and a ratio between the radii in the direction of the longaxes and the radii in the direction of the short axes of ellipticalshapes when the droplets are spread match.

FIG. 10 is a diagram that schematically illustrates a dropletarrangement pattern in a second nanoimprinting method.

FIG. 11A is a diagram that schematically illustrates the outer edges ofspread droplets in the case that there are two lattice points within aunit structure.

FIG. 11B is a diagram that schematically illustrates the outer edges ofspread droplets in the case that there is one lattice point within aunit structure.

FIGS. 12A and 12B are schematic diagrams for explaining rearrangement ofdroplets that approximate ellipses.

FIG. 13A is a diagram that schematically illustrates the relationshipbetween resolution and a droplet arrangement pattern in a conventionalink jet method.

FIG. 13B is a diagram that schematically illustrates the relationshipbetween resolution and a droplet arrangement pattern in an ink jetmethod of the present invention.

FIG. 14A is a first schematic diagram for explaining the relationshipamong the intervals among lattice points along a sub scanning direction,the arrangement interval among ink expelling outlets, and effectiveintervals among ink expelling outlets.

FIG. 14B is a second schematic diagram for explaining the relationshipamong the intervals among lattice points along a sub scanning direction,the arrangement interval among ink expelling outlets, and effectiveintervals among ink expelling outlets.

FIG. 14C is a third schematic diagram for explaining the relationshipamong the intervals among lattice points along a sub scanning direction,the arrangement interval among ink expelling outlets, and effectiveintervals among ink expelling outlets.

FIG. 15A is a first schematic diagram for explaining arrangementintervals among ink expelling outlets and effective intervals among inkexpelling outlets in the case that the ink expelling outlets of an inkjet head are arranged in a plurality of rows.

FIG. 15B is a second schematic diagram for explaining arrangementintervals among ink expelling outlets and effective intervals among inkexpelling outlets in the case that the ink expelling outlets of an inkjet head are arranged in a plurality of rows.

FIG. 16A is a schematic diagram for explaining the relationship amongthe intervals among lattice points along a sub scanning direction, thearrangement interval among ink expelling outlets, and effectiveintervals among ink expelling outlets of a third embodiment.

FIG. 16B is a schematic diagram for explaining the relationship amongthe intervals among lattice points along a sub scanning direction, thearrangement interval among ink expelling outlets, and effectiveintervals among ink expelling outlets of a fourth embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described withreference to the attached drawings. However, the present invention isnot limited to the embodiments to be described below. Note that in thedrawings, the dimensions of the constitutive elements are drawndifferently from the actual dimensions thereof, in order to facilitatevisual recognition thereof.

First Nanoimprinting Method

First, an embodiment of a first nanoimprinting method of the presentinvention will be described. Note that in this embodiment, photocuringnanoimprinting that cures a resist film with light will be described asan example of the first nanoimprinting method.

In the first nanoimprinting method, a quartz substrate is coated with aplurality of droplets that contain photocuring resin by the ink jetmethod such that the spaces among droplets in an A directionsubstantially parallel to the direction of lines of a linear pattern ofprotrusions and recesses are longer than the spaces among droplets in aB direction substantially perpendicular to the A direction within a linetransfer region of the quartz substrate that faces the linear pattern ofprotrusions and recesses of an Si mold (FIG. 1). Then, the linearpattern of protrusions and recesses of the Si mold is pressed onto thesurface of the quartz substrate which is coated with the droplets, tospread the droplets on the quartz substrate thereby forming aphotocuring resin film constituted by bonds among the spread pluralityof droplets. Thereafter, the photocuring resin film is exposed toultraviolet rays from the side of the quartz substrate to cure thephotocuring resin film. Finally, the Si mold is separated from thephotocuring resin film after it cures, to transfer the linear pattern ofprotrusions and recesses onto the photocuring resin film.

The photocuring resin film functions as a resist film during an etchingstep to be performed later. FIG. 1 is a diagram that schematicallyillustrates the relationship between the direction of lines of thelinear pattern of protrusions and recesses, and a coating arrangementfor the plurality of droplets that include photocuring resin, in thefirst imprinting method. Here, the expression “an A directionsubstantially parallel to the direction of the lines” of the linearpattern of protrusions and recesses includes directions, which arepractically equal to the direction of the lines of the linear pattern ofprotrusions and recesses, within a range that enables obtainment of theoperative effects of the present invention, in addition to the directionof the lines of the linear pattern of protrusions and recesses.Preferably, the expression “an A direction substantially parallel to thedirection of the lines” refers to directions within an angular range of±30 degrees from the direction of the lines, and more preferably todirections within an angular range of ±15 degrees from the direction ofthe lines. Meanwhile, the expression “a direction substantiallyperpendicular to the A direction” includes directions, which arepractically equal to the direction perpendicular to the A direction,within a range that enables the operative effects of the presentinvention to be obtained, in addition to the direction perpendicular tothe A direction. Preferably, the expression “a direction substantiallyperpendicular to the A direction” refers to directions within an angularrange of ±30 degrees from the direction perpendicular to the directionof the lines, and more preferably to directions within an angular rangeof ±15 degrees from the direction perpendicular tot he direction of thelines.

(Photocuring Resin)

The material of the photocuring resin is not particularly limited. Inthe present embodiment, a photocuring resin prepared by adding aphotopolymerization initiator (2% by mass) , a surfactant W-1 (0.1% bymass) , a surfactant W-2 (0.04% by mass) , an antioxidant A-1 (1% bymass), and an antioxidant A-2 (1% by mass) to a polymerizable compoundR-1. The photocuring resin produced by the above procedures can be curedby ultraviolet light having a wavelength of 360 nm. With respect toresins having poor solubility, it is preferable to add a small amount ofacetone or acetic ether to dissolve the resin, and then to remove thesolvent.

<Polymerizable Compound>

R-1: benzyl acrylate (V#160 by Osaka Organic Chemical Industries, K.K.)

<Photopolymerization Initiator>

P-1: 2,4,6-trimethylbenzoyl-ethoxyphenyl-phosphine oxide (Lucirin TPO-Lby BASF)

<Surfactants>

W-1: fluorochemical surfactant (fluorochemical surfactant by TochemProducts, K.K.)

W-2: silicone surfactant (Megafac Peintad 31 by Dainippon Ink ChemicalIndustries, K.K.)

<Antioxidant Agents>

A-1: Sumilizer GA80 by Sumitomo Chemical Industries, K.K. A-2: ADK STABA0503 by K.K. ADEKA

(Si Mold)

The Si mold to be utilized in the present embodiment may be produced bythe following procedures, for example. First, a Si substrate is coatedby a photoresist liquid such as a novolac resin or an acrylic resin bythe spin coat method or the like, to form a photoresist layer. Next, alaser beam (or an electron beam) is irradiated onto the Si substrate, toexpose a predetermined pattern on the surface of the photoresist layer.Then, the photoresist layer is developed to remove the exposed portions.Finally, selective etching is performed by RIE or the like, using thephotoresist layer after the exposed portions are removed, to obtain theSi mold having the predetermined pattern.

The mold to be employed in the imprinting method of the presentinvention may be that which has undergone a mold release process toimprove separation properties between the photocuring resin and themold. Examples of such a mold include: those which have been processedby silicone or fluorine silane coupling agents. Commercially availablemold release agents such as Optool DSX by Daikin Industries K.K. andNovec EGC-1720 by Sumitomo 3M K.K. may be favorably employed. Meanwhile,although the present embodiment is described as a case in which the Simold is employed, the mold is not limited to an Si mold, and a quartzmold may be employed. In this case, the quartz mold may be produced bythe method for producing a mold to be described later.

(Substrate)

The quartz substrate is employed to enable the photocuring resin to beexposed to light. The quartz substrate to be employed with the Si moldis not particularly limited as long as it has light transmissiveproperties and has a thickness of 0.3 mm or greater, and may be selectedas appropriate according to intended use. Examples of the quartzsubstrate include: those in which the surface of a quartz substrate iscoated with a silane coupling agent; those in which a metal layer of Cr,W, Ti, Ni, Ag, Pt, or Au is provided on the surface of a quartzsubstrate; those in which a metal oxide layer of CrO₂, WO₂, or TiO₂ isprovided on the surface of a quartz substrate; and those in which ametal layer of Cr, W, Ti, Ni, Ag, Pt, or Au or a metal oxide layer ofCrO₂, WO₂, or TiO₂ is provided on the surface of a quartz substrate,which is then coated with a silane coupling agent. The thickness of themetal layer or the metal oxide layer is generally 30 nm or less, andpreferably 20 nm or less. If the thickness of the metal layer or themetal oxide layer exceeds 30 nm, the UV transmissive propertiesdeteriorate, and curing failure of the photocuring resin becomes likelyto occur.

In addition, the expression “light transmissive properties” refers to adegree of light transmissivity that enables sufficient curing of thephotocuring resin film when light enters the side of the substrateopposite that on which the photocuring resin film is formed.Specifically, the “light transmissive properties” refers to lighttransmissivity of 5% or greater with respect to light having wavelengthsof 200 nm or greater from the side of the substrate opposite that onwhich the photocuring resin film is formed to the side of the substrateon which the photocuring resin film is formed.

It is preferable for the thickness of the quartz substrate to be 0.3 mmor greater. If the thickness of the quartz substrate is less than 0.3mm, it is likely to become damaged during handling or due to pressureduring imprinting.

Meanwhile, substrates to be employed with the quartz mold are notlimited with regard to the shape, the structure, the size or thematerial thereof, and may be selected according to intended use. Withrespect to the shape of the substrate, a substrate having a discoidshape may be utilized in the case that nanoimprinting is performed toproduce a data recording medium. With respect to the structure of thesubstrate, a single layer substrate maybe employed, or a laminatedsubstrate may be employed. With respect to the material of thesubstrate, the material may be selected from among known materials forsubstrates, such as silicon, nickel, aluminum, glass, and resin. Thesematerials may be utilized singly or in combination. The substrate may beproduced, or may be those which are commercially available. Thethickness of the substrate is not particularly limited, and may beselected according to intended use. However, it is preferable for thethickness of the substrate to be 0.05 mm or greater, and more preferably0.1 mm or greater. If the thickness of the substrate is less than 0.05mm, there is a possibility that the substrate will flex during closecontact with the mold, resulting in a uniform close contact state notbeing secured.

(Linear Pattern of Protrusions and Recesses)

Linear patterns of protrusions and recesses are formed on the Si mold aspatterns to be transferred. The expression “linear pattern ofprotrusions and recesses” refers to a pattern of protrusions andrecesses that causes anisotropy to occur in the spreading directions ofdroplets such that the shapes of the droplets approximate ellipses whenthe pattern is pressed against the droplets, due to the shape of thepattern. A pattern of protrusions and recesses that causes the long axesof the elliptical shapes of the plurality of droplets to be oriented ina single direction when the pattern is pressed against the droplets isreferred to as a “straight linear pattern of protrusions and recesses”.

The expression “direction of the lines of the linear pattern ofprotrusions and recesses” refers to a direction in which spreading ofthe droplets is facilitated, from along the directions along the patternformation surface of the mold. In other words, the expression “directionof the lines of the linear pattern of protrusions and recesses” refersto a direction along the long axes of the plurality of ellipses that thedroplets approximate when the linear pattern of protrusions and recessesis pressed against the droplets.

FIGS. 2A through 2D are diagrams that schematically illustrate examplesof linear patterns of protrusions and recesses. FIG. 2A, FIG. 2B, andFIG. 2C are schematic diagrams that illustrate patterns of protrusionsand recesses of the line and space type, in which elongated protrusions1 are arranged parallel to each other. FIG. 2D is a schematic diagramthat illustrates a pattern, in which rows of dot shaped protrusions 1,which are densely arranged in a single direction, are arranged parallelto each other. In these patterns, it is easier for the coated dropletsto spread within spaces between the protrusions 1. Therefore, anisotropyoccurs in the spreading of the droplets, and the shapes of the spreaddroplets approximate ellipses. Accordingly, the direction of the linesis a direction along the length direction of the elongate protrusions,or a direction along the length direction of the rows of denselyarranged dot shaped protrusions. FIG. 2A through FIG. 2D illustratecases in which the protrusions 1 are formed and/or arranged as straightlines. However, the linear patterns are not limited to straight linearpatterns, and the linear patterns may be formed or arranged such thatthey curve and/or zigzag. Note that FIG. 2E is a diagram thatschematically illustrates a pattern in which dot shaped protrusions 1are uniformly arranged in both vertically and horizontally. Becauseanisotropy does not clearly occur in the spreading direction ofdroplets, such a pattern is not a linear pattern of protrusions andrecesses as defined in the present specification.

As described previously, direction of the lines of the linear pattern ofprotrusions and recesses is the direction in which it is easy for thedroplets to spread. Therefore, in the case that the linear pattern ofprotrusions and recesses includes patterns of protrusions and recessesthat curve and/or zigzag, the direction of the lines will reflect suchshapes, and will be curves and/or zigzags. In these cases, the Adirection and the B direction are basically defined with the point thateach droplet is arranged as a reference.

However, in the case that the direction of the lines is curved or aplurality of straight linear directions within the linear pattern ofprotrusions and recesses, there are case in which it is necessary todefine a single straight linear direction as the direction of the linesof the linear pattern of protrusions and recesses, due to therelationship between a main scanning direction and a sub scanningdirection in the ink jet method. In such cases, the shapes of the linearpattern of protrusions and recesses are considered individually, and asingle straight linear direction is selected as the “direction of thelines” that reflects the linear pattern of protrusions and recesses. Theselection of such a direction may be performed by considering whichdirection the pressed droplets are easy to spread in as a whole, forexample. More specifically, the operation of pressing a plurality ofdroplets coated on a substrate with a linear pattern of protrusions andrecesses may be performed experimentally in advance. Then, a directionin which the greatest number of droplets spread may be selected as thesingle straight linear direction “that reflects the linear pattern ofprotrusions and recesses”. Note that such selection is not alwaysnecessary. For example, in the case that droplets are coated on adiscoid substrate while the substrate is being rotated, it is possibleto match the main scanning direction and the direction of the linesalong the circumference even if an ink jet head is fixed.

(Method for Coating the Photocuring Resin)

An ink jet printer is employed to arrange the droplets of photocuringresin onto the substrate. Examples of ink jet heads that expelphotocuring resin from nozzles include the piezoelectric type, thethermal type, and the electrostatic type. From among these, thepiezoelectric type of ink jet head, in which the amount of photocuringresin in each droplet and the expulsion speed are adjustable, ispreferable. The amount of photocuring resin in each droplet and theexpulsion speed are set and adjusted prior to arranging the droplets ofphotocuring resin onto the substrate. For example, it is preferable forthe amount of photocuring resin in each droplet to be adjusted to begreater at regions at which the spatial volume of the recesses of thepattern of protrusions and recesses is large, and to be smaller atregions at which the spatial volume of the recesses of the pattern ofprotrusions and recesses is small. The droplets are arranged on thesubstrate according to a predetermined droplet arrangement pattern afterthe adjustments are performed.

In the first nanoimprinting method of the present embodiment, it ispreferable for the resolution in the A direction which is defined by theink jet head that performs the coating with the droplets to be set lowerthan the resolution in the B direction which is defined by the ink jethead.

In the first nanoimprinting method of the present invention, it ispreferable for: one of the A direction and the B direction to be set asa main scanning direction in the ink jet method, and the other to be setas a sub scanning direction in the ink jet method; and for the ink jethead to be set such that the intervals among lattice points along thesub scanning direction is an integer multiple of effective intervalsamong ink expelling outlets of the ink jet head along the sub scanningdirection, when coating the droplets according to a droplet arrangementpattern constituted by a plurality of lattice points that correspond topositions at which each of the plurality of droplets are to be arranged.Note that details regarding the settings of the ink jet head will bedescribed later.

The droplet arrangement pattern is a two dimensional coordinate systemconstituted by a group of lattice points that correspond to thearrangement locations of the droplets, and include information regardingwhich regions of the substrate become line transfer regions or straightline transfer regions. As illustrated in FIG. 3B and FIG. 4B, the “linetransfer regions” and the “straight line transfer regions” refer toregions R1 and R2 that face a linear pattern of protrusions and recessesP1 and a straight linear pattern of protrusions and recesses P2 when thelinear pattern of protrusions and recesses P1 and the straight linearpattern of protrusions and recesses P2 are pressed against a substrate3. FIG. 3A is a diagram that schematically illustrates a mold 2 havingthe linear pattern of protrusions and recesses P1 formed thereon. FIG.3B is a diagram that schematically illustrates the substrate 3, ontowhich the mold 2 is pressed as a target of processing. FIG. 4A and FIG.4B are schematic sectional views taken along line I-I and line II-II ofFIG. 3A and FIG. 3B, respectively. The portions of the substrate 3illustrated in FIG. 4B that faces the patterns of protrusions andrecesses is the line transfer region R1 and the straight line transferregion R2.

The droplet arrangement pattern of the present embodiment has twodimensional coordinate information in which intervals among latticepoints along the A direction, which is substantially parallel to thedirection of the lines of the linear pattern of protrusions andrecesses, are greater than intervals among lattice points along the Bdirection, which is substantially perpendicular to the A direction.Thereby, the spaces among droplets in the A direction substantiallyparallel to the direction of the lines of the linear pattern ofprotrusions and recesses become longer than the spaces among droplets inthe B direction substantially perpendicular to the A direction.

This droplet arrangement pattern takes the fact that anisotropy occursin the spreading direction of the droplets along the direction of thelines of the linear pattern of protrusions and recesses intoconsideration. For example, FIG. 5A through FIG. 5C are diagrams thatschematically illustrate the manner in which droplets D, which areuniformily arranged on a transparent substrate such as a quartzsubstrate, spread as a flat plate 9 without a pattern of protrusions andrecesses thereon is pressed against the substrate. FIGS. 6A through 6Care diagrams that schematically illustrate the manner in which dropletsD, which are uniformly arranged on a transparent substrate, spread as amold 2 having a straight linear pattern of protrusions and recesses P2is pressed thereon. In the case illustrated in FIG. 5A through FIG. 5C,the droplets D spread isotropically. Therefore, no problems occur if thearrangement of the droplets D does not take the vertical and horizontaldirections into consideration, and a resist film 4 can be formed by theuniformly arranged droplets D. However, in the case illustrated in FIG.6A through FIG. 6C, the droplets D spread anisotropically. Therefore, ifthe amounts of resist in the droplets are the same, it is necessary totake the straight line direction A into consideration. That is, if thespaces among droplets Wa in the A direction and the spaces amongdroplets Wb in the B direction are equal, the amount of the droplets Din the A direction, in which it is easy for the droplets D to spread,will become excessive, and fluctuations will occur in the thickness ofthe resist film 4. At the same time, there will be an insufficientamount of the droplets D in the B direction, in which it is not easy forthe droplets D to spread, and there is a possibility that defects willoccur in the resist film 4 due to residual gas. Therefore, the presentinvention takes the direction of the lines A of the pattern ofprotrusions and recesses, that is, the ease and difficulty in thespreading of the droplets D, into consideration in the case that themold 2 having the straight linear pattern of protrusions and recesses P2is employed. Specifically, the arrangement of the droplets D is set suchthat the spaces among droplets Wa in the A direction are wide and thespaces among droplets Wb in the B direction are narrow, as illustratedin FIG. 7A through FIG. 7C. Thereby, fluctuations in the thickness ofthe resist film 4 and defects due to residual gas are suppressedcompared to cases in which the straight line direction A is not takeninto consideration.

It is preferable for a ratio Wa/Wb between an average space Wa betweendroplets in the A direction and an average space Wb between droplets inthe B direction to satisfy the following formula (1)

1.8≦Wa/Wb≦0.52V ^(1/3) /d   (1)

In formula (1), V represents the average volume of each coated droplet,and d represents a target average thickness of the resist film(including the residual layer), onto which the pattern of protrusionsand recesses is transferred following the spreading of the droplets.

The reason why the lower limit of the value of the ratio Wa/Wb is set to1.8 will be described. In the case that circular droplets are closelypacked and arranged as illustrated in FIG. 8, the space between dropletsWa in the A direction is approximately 1.73 times the space betweendroplets Wb in the B direction. Therefore, the droplets can be utilizedmore efficiently in cases that the droplets spread into ellipticalshapes, by setting the value of Wa/Wb to be a value greater than 1.73.

Meanwhile, the reason why the upper limit of the value of the ratioWa/Wb is set to 0.52V^(1/3)/d is because actual spreading of thedroplets in the A direction is limited by the average volume V of eachdroplet and the desired average thickness d of the resist film.Specifically, this value is derived as described below.

As illustrated in FIG. 9, it is preferable for elliptical droplets tospread via a state in which they simultaneously contact other ellipticaldroplets adjacent thereto in both the A direction (the direction of thelong axes) and the B direction (the direction of the short axes) as theshapes of the spreading droplets approximate ellipses, to minimizeoverlapping portions of the spread droplets when determining the dropletarrangement. This means that it is preferable for the value of Wa/Wb tobe the same as a ratio ra/rb between the radius ra of the ellipses inthe direction of the long axes and the radius rb of the ellipses in thedirection of the short axes. The range of values for Wa/Wb is determinedby the range of possible values for ra/rb.

Therefore, what the possible values for ra/rb are will be described inthe case that the volume of each coated droplet is V and the desiredaverage thickness of the resist film is d will be described hereinbelow.

First, V=πra·rb·d, and therefore, the following Formula (3) holds true.

$\begin{matrix}{\frac{ra}{rb} = \frac{V}{{\pi ({rb})}^{2}d}} & (3)\end{matrix}$

Generally, the radius rb of the short axis and the radius r of a dropletcontact surface prior to spreading (the radius of a circle thatapproximates the contact surface between the droplet prior to spreadingand the substrate) have the relationship rb≧r (rb=r is for cases inwhich the droplet does not spread in the B direction). Therefore, thepossible range of values for ra/rb can be expressed by the followingFormula (4).

$\begin{matrix}{\frac{ra}{rb} \leq \frac{V}{\pi \; r^{2}d}} & (4)\end{matrix}$

Meanwhile, the radius r of the droplet contact surface prior tospreading can be expressed by the following Formula (5), using thevolume V of the droplet and a contact angle θ.

$\begin{matrix}{r = \sqrt{\frac{V\; \sin^{3}\theta}{\pi \lbrack {{( {\cos^{3}\theta} )/3} - {\cos \; \theta} + {2/3}} \rbrack}}} & (5)\end{matrix}$

By substituting Formula (5) into Formula (4), Formula (6) below isobtained, and then Formula (7) is applied to obtain Formula (8).

$\begin{matrix}{\frac{ra}{rb} \leq {\frac{1}{\pi}\{ \frac{\sin^{3}\theta}{\pi \lbrack {{( {\cos^{3}\theta} )/3} - {\cos \; \theta} + {2/3}} \rbrack} \}^{{- 2}/3}\frac{V^{1/3}}{d}}} & (6) \\{{F(\theta)} = {\frac{1}{\pi}\{ \frac{\sin^{3}\theta}{\pi \lbrack {{( {\cos^{3}\theta} )/3} - {\cos \; \theta} + {2/3}} \rbrack} \}^{{- 2}/3}}} & (7) \\{\frac{ra}{rb} \leq {{F(\theta)}\frac{V^{1/3}}{d}}} & (8)\end{matrix}$

Here, F(θ) in Formula (7) is a function that depends only on the contactangle θ. Generally, it is preferable for the contact angle θ to besmall, considering close contact properties between the droplet and thesubstrate. The contact angle θ is set at least to be within a range from0°<θ≦90°, preferably within a range from 0°<θ≦30°, and more preferablywithin a range from 0°<θ≦10°. The following Formula (9) is obtained bytaking the facts that F(θ) is a monotonously increasing function in thecase that 0°<θ≦90° and 0<F(θ)≦0.52 into consideration.

$\begin{matrix}{\frac{ra}{rb} \leq {0.52\frac{V^{1/3}}{d}}} & (9)\end{matrix}$

The upper limit of the value of Wa/Wb was set to 0.52V^(1/3)/d for thereason described above.

(Mold Pressing Step)

The amount of residual gas is reduced by pressing the mold against thesubstrate after depressurizing the atmosphere between the mold and thesubstrate, or by causing the atmosphere between the mold and thesubstrate to be a vacuum. However, there is a possibility that thephotocuring resin will volatilize before curing in a vacuum environment,causing difficulties in maintaining a uniform film thickness. Therefore,it is preferable to reduce the amount of residual gas by causing theatmosphere between the substrate and the mold to be a He atmosphere or adepressurized He atmosphere. He passes through the quartz substrate, andtherefore the amount of residual gas (He) will gradually decrease. Asthe passage of He through the quartz substrate takes time, it is morepreferable for the depressurized He atmosphere to be employed.

The mold is pressed against the substrate at a pressure within a rangefrom 100 kPa to 10 MPa. The flow of the resin is promoted, the residualgas is compressed, the residual gas dissolves into the photocuringresin, and the passage of He through the quartz substrate is promoted asthe pressure is greater. However, if the pressure is excessive, there isa possibility that the mold and the substrate will be damaged if aforeign object is interposed between the mold and the substrate when themold contacts the substrate. Accordingly, it is preferable for thepressure to be within a range from 100 kPa to 10 MPa, more preferablywithin a range from 100 kPa to 5 MPa, and most preferably within a rangefrom 100 kPa to 1 MPa. The reason why the lower limit of the pressure isset to 100 kPa is that in the case that the space between the mold andthe substrate is filled with liquid when performing imprinting withinthe atmosphere, the space between the mold and the substrate ispressurized by atmospheric pressure (approximately 101 kPa).

(Mold Release Step)

After the mold is pressed against the substrate and the photocuringresin film is formed, the mold is separated from the photocuring resinfilm. As an example of a separating method, the outer edge portion ofone of the mold and the substrate may be held, while the rear surface ofthe other of the mold and the substrate is held by vacuum suction, andthe held portion of the outer edge or the held portion of the rearsurface is relatively moved in a direction opposite the pressingdirection.

As described above, the first nanoimprinting method of the presentinvention, the droplets are coated on the substrate such that the spacesamong droplets in the A direction substantially parallel to thedirection of the lines of the linear pattern of protrusions and recessesare longer than the spaces among droplets in the B directionsubstantially perpendicular to the A direction.

That is, the droplets are arranged taking the direction of the linesinto consideration. Therefore, the droplets can be spread evenly, evenif anisotropy occurs in the spreading direction of the droplets due tothe pattern shape of the linear pattern of protrusions and recesses. Asa result, fluctuations in thickness of residual resist film, on which apattern of protrusions and recesses has been transferred, and defectsdue to residual gas, can be suppressed in a nanoimprinting method thatperforms nanoimprinting after coating a substrate with droplets ofresist material using the ink jet method.

Second Nanoimprinting Method

Next, an embodiment of a second nanoimprinting method of the presentinvention will be described. Note that this embodiment will also bedescribed as an example in which photocuring nanoimprinting that cures aresist film with light is employed. The present embodiment differs fromthe previously described embodiment in the points that the linearpattern of protrusions and recesses is a straight linear pattern ofprotrusions and recesses, and that the droplet arrangement pattern isconstituted by a two dimensional coordinate system constituted by groupsof periodic lattice points. Accordingly, detailed descriptions regardingthe other constituent elements which are the same as those of thepreviously described embodiment will be omitted insofar as they are notparticularly necessary.

In the second nanoimprinting method, a quartz substrate is coated with aplurality of droplets that contain photocuring resin by the ink jetmethod according to a droplet arrangement pattern having basic unitlattices having periodicity in each of an A direction substantiallyparallel to the direction of the lines of the straight linear pattern ofprotrusions and in a B direction substantially perpendicular to the Adirection, and in which the periods of the periodicity in the Adirection are longer than the periods of the periodicity in the Bdirection, within a straight line transfer region of the quartzsubstrate that faces the straight linear pattern of protrusions andrecesses of an Si mold. Then, the straight linear pattern of protrusionsand recesses of the Si mold is pressed onto the surface of the quartzsubstrate which is coated with the droplets, to spread the droplets onthe quartz substrate thereby forming a photocuring resin filmconstituted by bonds among the spread plurality of droplets. Thereafter,the photocuring resin film is exposed to ultraviolet rays from the sideof the quartz substrate to cure the photocuring resin film. Finally, theSi mold is separated from the photocuring resin film after it cures, totransfer the straight linear pattern of protrusions and recesses ontothe photocuring resin film.

FIG. 10 is a diagram that schematically illustrates a dropletarrangement pattern in a second nanoimprinting method. The dropletarrangement patter of the present embodiment has two dimensionalcoordinate information, constituted by a plurality of lattice points Lwhich are arranged periodically. In other words, the droplet arrangementpattern of has basic unit lattices U having periodicity in both the Adirection and the B direction. In the present embodiment, the periods ofthe periodicity of the basic unit lattice U in the A direction and the Bdirection correspond to the spaces among droplets in the A direction andthe B direction of the previously described embodiment. A period Ta ofthe periodicity in the A direction is set to be longer than a period Tbof the periodicity in the B direction. With respect to the periodicityof the basic unit lattice U, it is preferable for a ratio Ta/Tb betweena length Ta of a single period in the A direction and a length Tb of asingle period in the B direction to satisfy the following formula (2) .The upper and lower limits are the same as those of Formula (1)described previously. However, V in Formula (2) V represents the averagevolume of droplets corresponding to representative lattice points of thebasic unit lattice U. Here, the representative lattice points of thebasic unit lattice U refers to lattice points of which the total volumeof the droplets corresponding thereto constitute a predetermined value(90% or greater) of the total volume of the droplets corresponding toall lattice points within the unit basic lattice U. It is not necessaryfor the representative lattice point to be a single point.

1.8≦Ta/Tb≦0.52V ^(1/3) /d   (2)

The designation of the basic unit lattice U is not particularly limited.For example, in FIG. 10, a parallelogram formed by a vector a and avector b of lengths corresponding to a single period of the periodicityin the A direction and the B direction, respectively, is designated asthe basic unit lattice U.

Considering the objective of suppressing fluctuations in thickness anddefects due to residual gas, as well as filling rates, it is preferablefor unit structures that constitute the basic unit lattice to include asingle lattice point L1=0·a+0·b, or the lattice point L1 and anotherlattice point L2=½·a+½·b. Here, a and b represent the vectors a and b.FIG. 11A is a diagram that schematically illustrates the outer edges ofspread droplets in the case that there are two lattice points within aunit structure. FIG. 11B is a diagram that schematically illustrates theouter edges of spread droplets in the case that there is one latticepoint within a unit structure. As illustrated in FIG. 11A and FIG. 11B,the resist film can be formed more efficiently by arranging the dropletsat points L1 and L2, even if the same number of droplets are coated. Inaddition, it is not necessary for the amounts of resist in all of thedroplets within the basic unit lattice U to be equal. For example,droplets of amounts that form the majority of the resist film may bearranged at the points L1, while droplets of amounts to a degree thatmerely fill in the gaps therebetween may be arranged at the points L2.

In the second nanoimprinting method of the present embodiment, it ispreferable for the resolution in the A direction which is defined by theink jet head that performs the coating with the droplets to be set lowerthan the resolution in the B direction which is defined by the ink jethead.

In the second nanoimprinting method of the present invention, it ispreferable for: one of the A direction and the B direction to be set asa main scanning direction in the ink jet method, and the other to be setas a sub scanning direction in the ink jet method; and for the ink jethead to be set such that the intervals among lattice points along thesub scanning direction is an integer multiple of effective intervalsamong ink expelling outlets of the ink jet head along the sub scanningdirection, when coating the droplets according to a droplet arrangementpattern constituted by a plurality of lattice points that correspond topositions at which each of the plurality of droplets are to be arranged.Note that details regarding the settings of the ink jet head will bedescribed later.

In the second nanoimprinting method of the present embodiment, thedroplets are coated onto the straight line transfer region of thesubstrate according to the droplet arrangement pattern. The dropletarrangement pattern has the basic unit lattices having periodicity inboth the A direction, which is substantially parallel to the directionof the lines of the linear pattern of protrusions and recesses, and theB direction, which is substantially perpendicular to the B direction.The periods of the periodicity in the A direction are longer than theperiods of the periodicity in the B direction, that is, the droplets arearranged taking the direction of the lines into consideration.Therefore, the second nanoimprinting method exhibits the sameadvantageous effects as those exhibited by the first nanoimprintingmethod.

Third Nanoimprinting Method and Method for Producing the DropletArrangement Pattern Employed therein

Next, an embodiment of a third nanoimprinting method of the presentinvention will be described. Note that this embodiment will also bedescribed as an example in which photocuring nanoimprinting that cures aresist film with light is employed. The present embodiment differs fromthe first embodiment in the point that a method for producing a dropletarrangement pattern of the present invention is executed, and thatdroplets are coated on a substrate according to a droplet arrangementpattern produced thereby. Accordingly, detailed descriptions regardingthe other constituent elements which are the same as those of thepreviously described embodiment will be omitted insofar as they are notparticularly necessary.

In the third nanoimprinting method, a quartz substrate is coated with aplurality of droplets that contain photocuring resin by the ink jetmethod according to a droplet arrangement pattern produced by a methodfor producing a droplet arrangement pattern of the present embodiment,within a line transfer region of the quartz substrate that faces alinear pattern of protrusions and recesses of an Si mold. Then, thelinear pattern of protrusions and recesses of the Si mold is pressedonto the surface of the quartz substrate which is coated with thedroplets, to spread the droplets on the quartz substrate thereby forminga photocuring resin film constituted by bonds among the spread pluralityof droplets. Thereafter, the photocuring resin film is exposed toultraviolet rays from the side of the quartz substrate to cure thephotocuring resin film. Finally, the Si mold is separated from thephotocuring resin film after it cures, to transfer the linear pattern ofprotrusions and recesses onto the photocuring resin film.

Meanwhile, the method for producing the droplet arrangement pattern ofthe present embodiment comprises the steps of: coating a plurality ofdroplets that contain the photocuring resin at a standard amount onto asecond quartz substrate different from the aforementioned quartzsubstrate; pressing a second Si mold having a pattern of protrusions andrecesses, which is the same as the linear pattern of protrusions andrecesses, against the surface of the second quartz substrate which iscoated with the droplets, to spread the droplets to a degree that thedroplets contact each other; causing the shapes of the spread dropletsof the standard amount to approximate ellipses; measuring thearrangement of the ellipses; rearranging the arrangements of themeasured ellipses such that the plurality of ellipses are closelypacked; and obtaining a droplet arrangement pattern constituted by aplurality of lattice points that correspond to positions at which theplurality of droplets are to be arranged, by designating the centers ofeach of the rearranged plurality of ellipses as lattice points.

In the present specification, the expression “standard amount” refers toan approximate amount of resist material within each droplet, whencoating the first substrate with the plurality of droplets of resistmaterial. Based on common expulsion performance of ink jet printers, thestandard amount is within a range from 1 pl to 1000 pl.

The droplet arrangement pattern is produced by the method for producinga droplet arrangement pattern of the present embodiment, based on thetwo dimensional shapes of the droplets which are spread during nanoimprinting.

The specific method and concept behind the method for producing thedroplet arrangement pattern are as follows. In the case that dropletsare already spread by a mold having a linear pattern of protrusions andrecesses, the droplets spread along the direction of the lines thereof.Therefore, the two dimensional shapes of the spread droplets approximateellipses. However, these two dimensional shapes depend greatly on thedesign of the pattern of the mold and on conditions regarding thedroplets which are utilized, and vary in a complex manner. For example,the two dimensional shapes of spread droplets vary according to theshape of a pattern (the height, the width, the pitch, the inclinationangle, etc. of the pattern), the two dimensional arrangement of thepattern (straight lines, curved lines, the repetitive structure of dots,whether dots and lines coexist), the coating conditions of droplets(volume per droplet, coating density, etc.), and the liquid propertiesof the droplets (viscosity, surface tension, etc.). Therefore, in thepresent embodiment, a test procedure, in which nanoimprinting isperformed using a mold having the same pattern of protrusions andrecesses, is executed to determine droplet arrangement conditions, priorto performing nanoimprinting employing a mold having a predeterminedpattern of protrusions and recesses. Thereby, a droplet arrangementpattern suited for executing nanoimprinting is produced.

The test procedure is performed by the following steps, for example. (1)A reference droplet arrangement pattern (a pattern in which droplets arearranged at lattice points of square lattices or triangular lattices,for example) is produced, and two dimensional shapes are repeatedlymeasured while gradually varying the amount of resin in the dropletswithin the range of the standard amount. (2) Two dimensional shapes arerepeatedly measured while gradually varying the spaces among droplets,which contain a reference amount of resin within the range of thestandard amount, within arrangement patterns. By repeating steps (1)and/or (2), conditions in which adjacent droplets which are spread bythe test mold do not contact each other are derived. The method formeasuring the two dimensional shapes is not particularly limited, and anoptical method or a stylus method may be employed. For example, anoptical microscope may be employed to obtain two dimensional images ofthe shapes, and the shapes may be measured by image processes. Inaddition, the measurement of the two dimensional images may be performedin a state in which the mold is pressed against the test substrate, orin a state in which the mold is separated from the test substrate. Thisis because the shapes of the droplets do not change much between thesetwo states if the droplets have been cured by exposure to light. Themeasured two dimensional shapes approximate ellipses by image processes.The approximation method is not particularly limited, but commonly,there are many cases in which the method of least squares is employed.Then, a two dimensional arrangement in which the ellipses are mostclosely packed is derived, by rearranging the arrangements of theapproximated ellipses (FIG. 12). Here, the most closely packedarrangement refers to a case in which the area occupied by the ellipseswithin the two dimensional image is 70% or greater. Finally, the centralcoordinates of the ellipses within the two dimensional arrangement areextracted, and two dimensional coordinates of a droplet arrangementhaving the coordinates as lattice points are obtained. Note that theaforementioned steps result in two dimensional coordinates of a dropletarrangement (droplet arrangement pattern) that considers the directionof the lines of the linear pattern of protrusions and recesses.Therefore, in the case that nanoimprinting is actually performed usingthis droplet arrangement pattern, it is necessary to finely adjust theamounts of resin in the droplets according to actual droplet coatingconditions.

In the third nanoimprinting method of the present invention, it ispreferable for the resolution in the direction of the long axes of theellipses which is defined by an ink jet head that performs the coatingwith the droplets to be set lower than the resolution in the directionof the short axes of the ellipses which is defined by the ink jet head.

In the third nanoimprinting method of the present invention, it ispreferable for one of the direction of the long axes and the directionof the short axes to be set as a main scanning direction in the ink jetmethod, and the other to be set as a sub scanning direction in the inkjet method; and

-   -   for the ink jet head to be set such that the intervals among        lattice points along the sub scanning direction is an integer        multiple of effective intervals among ink expelling outlets of        the ink jet head along the sub scanning direction, when coating        the droplets according to a droplet arrangement pattern        constituted by a plurality of lattice points that correspond to        positions at which each of the plurality of droplets are to be        arranged. Note that details regarding the settings of the ink        jet head will be described later.

As described above, in the third nanoimprinting method of the presentinvention, the droplets are coated on the substrate according to thedroplet arrangement pattern produced by the method for producing adroplet pattern of the present invention. The droplets are arrangedtaking the direction of the lines into consideration. Therefore, thethird nanoimprinting method exhibits the same advantageous effects asthose exhibited by the first nanoimprinting method.

Further, the method for producing a droplet arrangement pattern of thepresent invention comprises the steps of: coating a plurality ofdroplets of resist material at a standard amount onto a test substrate;pressing a test mold having a pattern of protrusions and recesses, whichis at least partially the same as the linear pattern of protrusions andrecesses, against the surface of the test substrate which is coated withthe droplets, to spread the droplets to a degree that the dropletscontact each other; causing the shapes of the spread droplets of thestandard amount to approximate ellipses; measuring the arrangement ofthe ellipses; rearranging the arrangements of the measured ellipses suchthat the plurality of ellipses are closely packed; and obtaining adroplet arrangement pattern constituted by a plurality of lattice pointsthat correspond to positions at which the plurality of droplets are tobe arranged, by designating the centers of each of the rearrangedplurality of ellipses as lattice points. As a result, a dropletarrangement pattern that takes the direction of the lines of the linearpattern of protrusions and recesses into consideration is obtained.Thereby, fluctuations in thickness of residual resist film, on which apattern of protrusions and recesses has been transferred, and defectsdue to residual gas, can be suppressed in a nanoimprinting method thatperforms nanoimprinting after coating a substrate with droplets ofresist material using the ink jet method, by utilizing the dropletarrangement pattern produced in this manner.

<Design Modifications>

The embodiments of the first through third nanoimprinting methods andthe method for producing a droplet arrangement pattern above have beendescribed as cases in which photocuring nanoimprinting that cures resistfilms with light is employed. However, the present invention is notlimited to such a configuration, and may also be applied to thermalcuring nanoimprinting that employs thermal curing resin.

Method for Setting Ink Jet Head in the Nanoimprinting Methods of thePresent Invention

In the present embodiment, a case will be described in which theresolution in the A direction which is defined by an ink jet head thatperforms the coating with the droplets is set to be lower than theresolution in the B direction which is defined by the ink jet head. Notethat with respect to the third nanoimprinting method of the presentinvention, the “A direction” and the “B direction” designate the“direction of the long axes” and the “direction of the short axes” ofthe rearranged ellipses, respectively.

The expression “resolution . . . which is defined by an ink jet head”refers to indices of arrangement performance (the fineness of a grid tobe described later) that indicate at what density droplets can bearranged. These indices are determined by the intervals among inkexpelling outlets, the expulsion frequency, and the scanning speed ofthe ink jet head. FIG. 13A is a diagram that schematically illustratesthe relationship between resolution and a droplet arrangement pattern ina conventional ink jet method. FIG. 13B is a diagram that schematicallyillustrates the relationship between resolution and a dropletarrangement pattern in an ink jet method of the present invention. Inthe figures, BM denotes a map (bitmap) of a grid in which droplets canbe arranged by an ink jet printer, and L denotes lattice points thatcorrespond to the positions at which the droplets are arranged. The inkjet method is executed by the ink jet head scanning each grid of the bitmap BM on the substrate while referring to the droplet arrangementpattern, and coating droplets onto portions of the grid that correspondto the lattice points L of the droplet arrangement pattern.

In the conventional drop on demand method, arrangements that maximizedroplet arrangement density are said to be preferable. Accordingly, asillustrated in FIG. 13A, the resolution of the bitmap is high (the gridsare small), and the resolution is set to be equal in both the mainscanning direction and the sub scanning direction. However, dropletsspread anisotropically when they contact patterns having anisotropy,such as a linear pattern of protrusions and recesses. That is, in suchcases, the drop on demand method that assumes isotropic spreading ofdroplets is not effective.

On the other hand, it is not necessary for the resolution to be the samein the A direction and the B direction within regions in which theintervals among lattice points of the droplet arrangement pattern arelonger in the A direction than in the B direction, in the nanoimprintingmethods of the present invention. Further, it is not necessary toperform finer scanning in the A direction than in the B direction.Therefore, maximization of the droplet arrangement density, which hadheretofore been considered necessary, is purposely not performed in thenanoimprinting methods of the present invention, and resolution, whichhad been at excessive performance levels, is reduced. Thereby, thethroughput of the droplet coating process can be improved. Morespecifically, the shape of the grids of the bitmap BM are set asrectangles which are long in the A direction as illustrated in FIG. 13B,and the resolution in the A direction is set to be less than theresolution in the B direction. By setting the resolution in this manner,throughput during droplet discharge can be improved, while maintainingthe resolution performance of the ink jet printer as a whole, becausenecessary resolution is maintained in the B direction, while obviatingfine scanning in the A direction.

Note that the main scanning direction in the ink jet method may beeither one of the A direction and the B direction. In the case that theA direction is the main scanning direction, the main scanning speed canbe accelerated because the resolution in the main scanning direction islow. As a result, the amount of time required for coating during eachscanning operation is reduced, and the total coating time can bereduced. In the case that the B direction is the main scanningdirection, the resolution in the stage feeding direction is low, andtherefore the number of scanning operations in the sub scanningdirection can be reduced. As a result, the total coating time can bereduced.

As described above, the nanoimprinting methods of the present inventionmay adopt a configuration, wherein: the resolution in the A directionwhich is defined by an ink jet head that performs the coating with thedroplets is set to be lower than the resolution in the B direction whichis defined by the ink jet head. In this case, throughput during dropletdischarge can be improved, while maintaining the resolution performanceof the ink jet printer as a whole.

Next, a case will be described, in which one of the A direction and theB direction is set as a main scanning direction in the ink jet method,and the other is set as a sub scanning direction in the ink jet method;and the ink jet head is set such that the intervals among lattice pointsalong the sub scanning direction is an integer multiple of effectiveintervals among ink expelling outlets of the ink jet head along the subscanning direction, when coating the droplets according to a dropletarrangement pattern constituted by a plurality of lattice points thatcorrespond to positions at which each of the plurality of droplets areto be arranged.

In the present specification, the expression “intervals among latticepoints along the sub scanning direction” refers to the smallest distancein the sub scanning direction between a lattice point and anotherlattice point. That is, in the case of a droplet arrangement patternhaving L1 and L2 as a unit structure as illustrated in FIG. 10, theintervals among lattice points along the sub scanning direction is halfthe period which is set along the sub scanning direction. In addition,the expression “effective intervals among ink expelling outlets” refersto the smallest distance in the sub scanning direction between an inkexpelling outlet and another ink expelling outlet. Accordingly, theeffective intervals among ink expelling outlets” in the case that theexpelling outlets are provided in a row with predetermined arrangementintervals therebetween, the effective intervals are equal to thearrangement intervals.

Specifically, setting of the ink jet head described above is executed inthe following manner. FIG. 14A through FIG. 14C are schematic diagramsfor explaining the relationship among the intervals among lattice pointsalong a sub scanning direction, the arrangement interval among inkexpelling outlets, and effective intervals among ink expelling outlets.Note that in FIG. 14A through FIG. 14C, the A direction is designated asa main scanning direction Sm, and the B direction is designated as a subscanning direction Sv. In addition, the intervals among lattice pointsmatch the period of the lattice points in FIG. 14A through FIG. 14C.

FIG. 14A illustrates a case in which intervals Lb among lattice points Lalong the sub scanning direction Sv and arrangement intervals x of inkexpelling outlets 12 of an ink jet head 10 are matched. Meanwhile, FIG.14B illustrates a case in which intervals Lb among lattice points Lalong the sub scanning direction Sv and arrangement intervals x of inkexpelling outlets 12 of an ink jet head 10 have the relationship Lb=2x.That is, as described above, an ink jet head having an arrangementinterval x that satisfies the relationship Lb=nx (n is a positiveinteger) with respect to the intervals among lattice points Lb may beselected. In the case that the arrangement interval x does not satisfythe above relationship, the arrangement direction of the ink expellingoutlets may be inclined by an angle θ with respect to the sub scanningdirection, to adjust effective intervals y among the ink expellingoutlets such that the relationship Lb=ny (n is a positive integer) issatisfied. In such a case, x and y have the relationship y=x·cosθ. Here,the angle θ is an acute angle formed between the sub scanning directionSv and a direction G of the inclined ink jet head.

In addition, an ink jet head 10 provided with a plurality of rows of inkexpelling outlets may also be utilized. For example, FIG. 15A and FIG.15B are schematic diagrams for explaining arrangement intervals amongink expelling outlets and effective intervals among ink expellingoutlets in the case that the ink expelling outlets of an ink jet headare arranged in a plurality of rows. The ink jet heads 10 of FIG. 15Aand FIG. 15B are constituted by ink jet heads 10 a and 10 b, each ofwhich has ink expelling outlets arranged with predetermined intervalstherebetween. In these cases, whether ink expelling outlets (12 a and 12b) are in the same or different rows is not taken into consideration.That is, the arrangement intervals x among the ink expelling outlets ofsuch inkjet heads 10 are the intervals among the ink expelling outlets12 a of the ink jet head 10 a and the ink expelling outlets 12 b of theink jet head 10 b along the sub scanning direction Sv (FIG. 15A). In thecase that the rows of ink expelling outlets are inclined with respect tothe sub scanning direction Sv, the effective intervals y among the inkexpelling outlets are the intervals among the ink expelling outlets 12 aof the ink jet head 10 a and the ink expelling outlets 12 b of the inkjet head 10 b along the sub scanning direction Sv (FIG. 15B).

As described above, in the case that the intervals among lattice pointsalong the sub scanning direction are not integer multiples of theeffective intervals among the ink expelling outlets of the ink jet headalong the sub scanning direction, it is necessary to perform repeatedscanning operations with different settings, and a great number ofscanning operations will become necessary. However, by setting the inkjet head such that the intervals among lattice points along the subscanning direction are integer multiples of the effective intervalsamong the ink expelling outlets of the ink jet head along the subscanning direction, droplets can be coated efficiently, and throughputduring droplet expulsion can be improved further.

In addition, in the case that there are regions having differentintervals among lattice points, the greatest common denominator of theintervals among lattice points may be set as the arrangement interval x(or the effective interval y) among ink expelling outlets along the subscanning direction. Thereby, such regions can be coated with dropletswith a single scanning operation.

As described above, the nanoimprinting methods of the present inventionmay adopt configurations in which: one of the A direction and the Bdirection to be set as a main scanning direction in the ink jet method,and the other to be set as a sub scanning direction in the ink jetmethod; and the ink jet head to be set such that the intervals amonglattice points along the sub scanning direction is an integer multipleof effective intervals among ink expelling outlets of the ink jet headalong the sub scanning direction, when coating the droplets according toa droplet arrangement pattern constituted by a plurality of latticepoints that correspond to positions at which each of the plurality ofdroplets are to be arranged. In this case, the droplets can be coatedefficiently, and throughput during droplet expulsion can be improvedfurther.

Method for Producing a Substrate

Next, an embodiment of a method for producing a substrate of the presentinvention will be described. The present embodiment will be described asa case in which a substrate is produced by the first nanoimprintingmethod described previously, employing a Si mold an original plate.

First, a resist film, on which a pattern has been transferred by thefirst nanoimprinting method, is formed on a surface of a substrate.Then, dry etching is performed using the resist film having thetransferred pattern as a mask, to form a pattern of protrusions andrecesses corresponding to the pattern of protrusions and recesses of theresist film. Thereby, a substrate having a predetermined pattern isobtained.

In the case that the substrate is of a layered structure and includes ametal layer on the surface thereof, dry etching is performed using theresist film as a mask, to form a pattern of protrusions and recessescorresponding to the pattern of protrusions and recesses of the resistfilm in the metal layer. Thereafter, dry etching is further performedwith the thin metal layer as an etching stop layer, to form a pattern ofprotrusions and recesses in the substrate. Thereby, a substrate having apredetermined pattern is obtained.

The dry etching method is not particularly limited as long as it iscapable of forming a pattern of protrusions and recesses in thesubstrate, and may be selected according to specific objectives.Examples of dry etching methods that may be employed include: the ionmilling method; the RIE (Reactive Ion Etching) method; the sputteretching method; etc. From among these methods, the ion milling methodand the RIE method are particularly preferred.

The ion milling method is also referred to as ion beam etching. In theion milling method, an inert gas such as Ar is introduced into an ionsource, to generate ions. The generated ions are accelerated through agrid and caused to collide with a sample substrate to perform etching.Examples of ion sources include: Kauffman type ion sources; highfrequency ion sources; electron bombardment ion sources; duoplasmatronion sources; Freeman ion sources; and ECR (Electron Cyclotron Resonance)ion sources.

Ar gas may be employed as a processing gas during ion beam etching.Fluorine series gases or chlorine series gases may be employed asetchants during RIE.

As described above, the method for producing a substrate of the presentinvention performs dry etching, using the resist film onto which apattern is transferred by the nanoimprinting method of the presentinvention as a mask. That is, a mask free of fluctuations in thethickness of a residual layer and also free from defects due to residualgas is employed to perform dry etching. Therefore, it becomes possibleto produce substrates highly accurately at high yield.

<Design Modifications>

Note that the embodiment of the method for producing a substratedescribed above was described as an example in which the resist filmformed by the first nanoimprinting method was employed as the mask.However, the present invention is not limited to this configuration, anda resist film formed by the second or the third nanoimprinting methodmay alternatively be employed as the mask.

Hereinafter, embodiments of the present invention will be described.

Embodiment 1

(Production of Si mold)

First, a Si substrate was coated with a photoresist liquid having PMMA(polymethyl methacrylate) as a main component by the spin coat method,to form a photoresist layer. Thereafter, an electron beam, which wasmodulated according to a concentric pattern having a line width of 100nm and a pitch of 200 nm, was irradiated onto the photoresist layerwhile rotating the Si substrate, to expose the concentric pattern withina range from a radius of 15 mm to 30 mm. Thereafter, the photoresistlayer underwent a development process and the exposed portions wereremoved. Finally, selective etching was performed to a depth of 80 nm byRIE using the photoresist layer, from which the exposed portions wereremoved, as a mask, to obtain a first Si mold having the concentricpattern.

(Photocuring Resin)

The aforementioned photocuring resin, prepared by adding aphotopolymerization initiator (2% by mass), a surfactant W-1 (0.1% bymass), a surfactant W-2 (0.04% by mass), an antioxidant A-1 (1% bymass), and an antioxidant A-2 (1% by mass) to a polymerizable compoundR-1, was employed.

(Substrate)

The surface of a 0.525 mm thick quartz wafer was processed with KBM-5103(by Shin-Etsu Chemical Industries, K.K.) , which is a silane couplingagent having superior close contact properties with respect to thephotocuring resin. The KBM-5103 was diluted to 1% by mass using PGMEA(Propylene Glycol Monomethyl Ether Acetate), and coated on the surfaceof the substrate by the spin coat method. Thereafter, the coatedsubstrate was annealed for 20 minutes at 120° C. on a hot plate, causingthe silane coupling agent to bond to the surface of the substrate.

(Photocuring Resin Coating Step)

DMP-2831, which is an ink jet printer of the piezoelectric type byFUJIFILM Dimatix, was utilized. DMC-11610, which is a dedicated 10 plhead, was utilized as an ink jet head. Ink expelling conditions were setand adjusted in advance such that the amount of resin in each dropletwas 10 pl. A droplet arrangement pattern was produced by the method forproducing a droplet arrangement pattern of the present invention. Thespaces among droplets Wa and Wb in the droplet arrangement pattern were1000 μm and 250 μm, respectively. Then, the ink expelling conditionswere set and adjusted in advance, and droplets were arranged in a linetransfer region according to the droplet arrangement pattern.

(Si Mold Pressing Step)

The droplet arrangement pattern and the pattern of protrusions andrecesses of the Si mold. Specifically, the Si mold and the quartzsubstrate were caused to approach each other such that the gaptherebetween was 0.1 mm or less. Next, the droplet arrangement patternand the pattern of protrusions and recesses of the mold were observedwith a microscope from the underside of the quartz substrate, and the Simold or a stage that the quartz substrate was placed on was moved suchthat the positions thereof matched. The space between the Si mold andthe quartz substrate was replaced with a gas which is 99% He by volumeor greater. Then, depressurization was performed to 50 kPa, to form adepressurized He environment. The Si mold was caused to contact thedroplets under the depressurized He conditions. After contact, themanner in which the droplets spread was observed with a microscope fromthe underside of the quartz substrate, and an image of the ellipticalshapes during the droplet spreading process was obtained. The contactstate was maintained for one minute, and ultraviolet light including awavelength of 360 nm as irradiated at a dosage of 300 mJ/cm², to curethe photocuring resin.

(Si Mold Release Step)

The outer edge portion of the quartz substrate was held, and the Si moldwas relatively moved in a direction opposite the pressing directionwhile the rear surface of the Si mold was held by vacuum suction, torelease and separate the Si mold. Thereby, a first photocuring resinfilm, on which the pattern of protrusions and recesses is transferred,was obtained.

(Quartz Substrate Processing Step)

Dry etching was performed as described below using the photocuring resinfilm, on which the pattern of protrusions and recesses is transferred,as a mask. Thereby, shapes of protrusions and recesses based on thepattern of protrusions and recesses of the photocuring resin film wereformed on the quartz substrate, to obtain a first quartz mold having apredetermined pattern of protrusions and recesses. First, the residuallayer present at the recesses of the pattern was removed by oxygenplasma etching, to expose the quartz substrate at the recesses of thepattern. At this time, conditions were set such that the amount ofetching is capable of removing the thickest residual layer within theregion of the pattern of protrusions and recesses. Next, RIE using afluorine series gas was administered on the quartz substrate, using theprotrusions of the pattern as a mask. The RIE conditions were set suchthat the depth of etching was 80 nm. Finally, the residue of theprotrusions of the pattern was removed by oxygen plasma etching.

Embodiment 2

(Production of Si mold)

An electron beam, which was modulated according to a straight linearpattern of protrusions and recesses having a line width of 100 nm and apitch of 200 nm, was irradiated onto the entire surface of a 10 mmsquare photoresist layer while rotating the Si substrate, to expose thestraight linear pattern of protrusions and recesses. Thereafter, thesame steps as those described with respect to Embodiment 1 wereperformed, to obtain a second Si mold having the straight linear patternof protrusions and recesses.

The second Si mold was employed to execute the same steps as thosedescribed with respect to Embodiment 1, to obtain a second photocuringresin film on which the pattern of protrusions and recesses wastransferred, and a second quartz mold having a predetermined pattern ofprotrusions and recesses.

Comparative Example 1

The same steps as those described with respect to Embodiment 1, exceptthat the spaces among droplets Wa and Wb were both 500 μm, wereexecuted, to obtain a photocuring resin film on which a pattern ofprotrusions and recesses was transferred, and a quartz mold having apredetermined pattern of protrusions and recesses.

Comparative Example 2

The same steps as those described with respect to Embodiment 2, exceptthat the spaces among droplets Wa and Wb were both 500 μm, wereexecuted, to obtain a photocuring resin film on which a pattern ofprotrusions and recesses was transferred, and a quartz mold having apredetermined pattern of protrusions and recesses.

(Evaluation Method)

The patterns of protrusions and recesses of the photocuring resin filmsobtained by Embodiments 1 and 2 as well as Comparative Examples 1 and 2were inspected by performing dark field measurements with an opticalmicroscope (magnification: 50× to 1500×).

First, 2 mm square fields were defined at a magnification of 50×. Next,the measurement fields were scanned, to ascertain the presence ofdefects due to residual gas. Defects due to residual gas were judged tobe present in cases that scattered light, which should not be present ina normal pattern, was observed. The total number of defects due toresidual gas was counted. In the case that the number of defects per lcmsquare area was 0, it was judged that no defects were present (GOOD). Inthe case that the number of defects per 1 cm square area was 1 or more,it was judged that defects were present (POOR).

Next, the thicknesses of the residual layers of the photocuring resinfilms were measured. The substrates were exposed by scratching orremoving portions of the patterned regions of the photocuring resinfilms, and the thicknesses of the residual layers were measured bymeasuring the boundary portions between the removed portions and thepattern regions by an AFM (Atomic Force Microscope). The thicknesses ofthe residual layers were measured at 10 locations within each patternregion, and it was judged that fluctuations in film thickness were notpresent (GOOD) in cases that the standard deviation among the 10measured values was less than 20 nm, and that fluctuations in filmthickness were present (POOR) in cases that the standard deviation amongthe 10 measured values was 20 nm or greater.

The patterns of protrusions and recesses of the quartz molds ofEmbodiments 1 and 2 as well as Comparative Examples 1 and 2 were alsoinspected by performing dark field measurements with an opticalmicroscope (magnification: 50× to 1500×).

Evaluation Results of Embodiments 1 and 2

As illustrated in Table 1, the photocuring resin films of Embodiments 1and 2 accurately reflected the patterns of protrusions and recesses ofthe Si molds without defects or fluctuations in the thicknesses of theresidual layers. In addition, quartz molds having uniform line widthsand pattern heights were obtained, and it was confirmed that the presentinvention is capable of producing favorable substrates.

TABLE 1 Spaces Among Pattern Droplets Evaluation Results Type Wa (μm) Wb(μm) Defects Thickness Embodiment 1 Linear 1000 250 GOOD GOODComparative Linear 500 500 POOR POOR Example 1 Embodiment 2 Straight1000 250 GOOD GOOD Linear Comparative Straight 500 500 POOR POOR Example2 Linear

Embodiment 3

An Si mold was produced in the same manner as in Embodiment 2, aphotocuring resin and a substrate were prepared in the same manner asEmbodiment 2, and the following coating step was executed. Thereafter,an evaluation was performed regarding the amount of coating timenecessary to coat droplets.

(Photocuring Resin Coating Step)

DMP-2831, which is an ink jet printer of the piezoelectric type byFUJIFILM Dimatix, was utilized. DMC-11601, which is a dedicated 1 plhead, was utilized as an ink jet head. Ink expelling conditions were setand adjusted in advance such that the amount of resin in each dropletwas 1 pl. A droplet arrangement pattern was produced by the method forproducing a droplet arrangement pattern of the present invention. Theintervals among lattice points La and Lb in the droplet arrangementpattern along the A direction and the B direction were 316 μm and 79 μm,respectively.

DMC-11601 is provided with 16 ink expelling outlets at intervals of 254μm therebetween. Because the intervals among lattice points of thedroplet arrangement pattern is less than 254 μm or less, the head isrotated for an angle θ₁ with respect to the sub scanning direction, tochange the effective intervals among adjacent ink expelling outletsalong the sub scanning direction to a desired distance. Note that in thecase that the intervals among lattice points of the droplet arrangementpattern is greater than 254 μm, the ink expelling outlets to be utilizeday be thinned, or the effective intervals among adjacent ink expellingoutlets is adjusted by rotating the head such that the effectiveintervals become desired values. The effective intervals among inkexpelling outlets of the ink jet head was adjusted to become an integermultiple of the intervals among lattice points in the sub scanningdirection as described above.

The direction to be designated as the main scanning direction is notparticularly limited. However, the B direction was set as the mainscanning direction and the A direction was set as the sub scanningdirection in the present embodiment. The resolution in the A directionwas adjusted by the angle of rotation of the head, and the resolution inthe B direction was adjusted by scanning speed at a predeterminedexpulsion frequency, to set the resolution in the A direction to 80 dpi,and the resolution in the B direction to 322 dpi. That is, theresolution in the A direction was set to be smaller than the resolutionin the B direction. Note that the effective interval among ink expellingoutlets was 79 μm (FIG. 16A).

The coating time is determined by the number of scanning operations,stage feeding time, etc. In the present embodiment, the coating timerequired to coat the droplets was designated as T.

Under the conditions described above, the droplets were arranged withina straight line transfer region according to the droplet arrangementpattern.

Embodiment 4

Droplets were arranged in the same manner as in Embodiment 3, exceptthat an ink jet head was rotated for an angle θ₂ to adjust the effectiveinterval among ink expelling outlets to 158 θm (FIG. 16B) .

Comparative Example 3

Droplets were arranged in the same manner as in Embodiment 3, exceptthat the resolution in the A direction was set to 322 dpi by aconventional method to match the resolution in the B direction of 322dpi.

Evaluation Results of Embodiments 3 and 4

As illustrated in Table 2, the time required to coat droplets wasshortened to ¼ that of a conventional method in Embodiment 3, and to ⅛that of a conventional method in Embodiment 4. As a result, it wasconfirmed that the present invention realizes improvement of throughputduring droplet discharge, while maintaining the resolution performanceof the ink jet printer as a whole.

TABLE 2 Effective Intervals Intervals Among Among Lattice Ink JetResolution Ink Points (dpi) Expelling (μm) A B Outlets Coating La LbDirection Direction (μm) Time Embodiment 3 316 79 80 322 79 TComparative 316 79 322 322 79 4T Example 3 Embodiment 4 316 79 80 322158 0.5T

1-20. (canceled)
 21. A nanoimprinting method, comprising: coating asubstrate with a plurality of droplets of resist material by the ink jetmethod; and pressing a linear pattern of protrusions and recesses of amold onto the surface of the substrate which is coated with thedroplets, to spread the droplets on the substrate, to form a resist filmconstituted by bonds among the spread plurality of droplets and totransfer the linear pattern of protrusions and recesses onto the resistfilm; the droplets being coated on the substrate such that the spacesamong droplets in an A direction substantially parallel to the directionof the lines of the linear pattern of protrusions and recesses arelonger than the spaces among droplets in a B direction substantiallyperpendicular to the A direction within a line transfer region of thesubstrate that faces the linear pattern of protrusions and recesses whenthe linear pattern of protrusions and recesses is pressed against thesubstrate.
 22. A nanoimprinting method as defined in claim 21, wherein:a ratio Wa/Wb between an average space Wa between droplets in the Adirection and an average space Wb between droplets in the B directionsatisfy the following formula (1)1.8≦Wa/Wb≦0.52V ^(1/3) /d   (1) wherein V represents the average volumeof each coated droplet, and d represents the average thickness of theresist film.
 23. A nanoimprinting method as defined in claim 21,wherein: the resolution in the A direction which is defined by an inkjet head that performs the coating with the droplets is set to be lowerthan the resolution in the B direction which is defined by the ink jethead.
 24. A nanoimprinting method as defined in claim 22, wherein: theresolution in the A direction which is defined by an ink jet head thatperforms the coating with the droplets is set to be lower than theresolution in the B direction which is defined by the ink jet head. 25.A nanoimprinting method as defined in claim 23, wherein: one of the Adirection and the B direction is set as a main scanning direction in theink jet method, and the other is set as a sub scanning direction in theink jet method; and the ink jet head is set such that the intervalsamong lattice points along the sub scanning direction is an integermultiple of effective intervals among ink expelling outlets of the inkjet head along the sub scanning direction, when coating the dropletsaccording to a droplet arrangement pattern constituted by a plurality oflattice points that correspond to positions at which each of theplurality of droplets are to be arranged.
 26. A nanoimprinting method asdefined in claim 24, wherein: one of the A direction and the B directionis set as a main scanning direction in the ink jet method, and the otheris set as a sub scanning direction in the ink jet method; and the inkjet head is set such that the intervals among lattice points along thesub scanning direction is an integer multiple of effective intervalsamong ink expelling outlets of the ink jet head along the sub scanningdirection, when coating the droplets according to a droplet arrangementpattern constituted by a plurality of lattice points that correspond topositions at which each of the plurality of droplets are to be arranged.27. A nanoimprinting method, comprising: coating a substrate with aplurality of droplets of resist material by the ink jet method; andpressing a straight linear pattern of protrusions and recesses of a moldonto the surface of the substrate which is coated with the droplets, tospread the droplets on the substrate, to form a resist film constitutedby bonds among the spread plurality of droplets and to transfer thestraight linear pattern of protrusions and recesses onto the resistfilm; the droplets being coated on the substrate according to a dropletarrangement pattern constituted by a plurality of lattice points thatcorrespond to positions at which each of the plurality of droplets areto be arranged within a straight line transfer region of the substratethat faces the straight linear pattern of protrusions and recesses whenthe straight linear pattern of protrusions and recesses is pressedagainst the substrate; and the droplet arrangement pattern having basicunit lattices having periodicity in each of an A direction substantiallyparallel to the direction of the lines of the straight linear pattern ofprotrusions and recesses and in a B direction substantiallyperpendicular to the A direction, and the periods of the periodicity inthe A direction being longer than the periods of the periodicity in theB direction.
 28. A nanoimprinting method as defined in claim 27,wherein: each basic unit lattice is a unit structure that includeslattice points L1=0·a+0·b and L2=½·a+½·b, in the case that an initialpoint for a vector a that represents a single period in the A directionand an initial point for a vector b that represents a single period inthe B direction are set at a single lattice point, and the basic unitlattice is designated as a parallelogram formed by the vector a and thevector b.
 29. A nanoimprinting method as defined in claim 27 , wherein:a ratio Ta/Tb between a length Ta of a single period in the A directionand a length Tb of a single period in the B direction satisfy thefollowing formula (2)1.8≦Ta/Tb0.52V ^(1/3) /d   (2) wherein V represents the average volumeof droplets corresponding to representative lattice points of the basicunit lattice, and d represents the average thickness of the resist film.30. A nanoimprinting method as defined in claim 28, wherein: a ratioTa/Tb between a length Ta of a single period in the A direction and alength Tb of a single period in the B direction satisfy the followingformula (2)1.8≦Ta/Tb0.52V ^(1/3) /d   (2) wherein V represents the average volumeof droplets corresponding to representative lattice points of the basicunit lattice, and d represents the average thickness of the resist film.31. A nanoimprinting method as defined in claim 27, wherein: theresolution in the A direction which is defined by an ink jet head thatperforms the coating with the droplets is set to be lower than theresolution in the B direction which is defined by the ink jet head. 32.A nanoimprinting method as defined in claim 28, wherein: the resolutionin the A direction which is defined by an ink jet head that performs thecoating with the droplets is set to be lower than the resolution in theB direction which is defined by the ink jet head.
 33. A nanoimprintingmethod as defined in claim 29, wherein: the resolution in the Adirection which is defined by an ink jet head that performs the coatingwith the droplets is set to be lower than the resolution in the Bdirection which is defined by the ink jet head.
 34. A nanoimprintingmethod as defined in claim 30, wherein: the resolution in the Adirection which is defined by an ink jet head that performs the coatingwith the droplets is set to be lower than the resolution in the Bdirection which is defined by the ink jet head.
 35. A nanoimprintingmethod as defined in claim 31, wherein: one of the A direction and the Bdirection is set as a main scanning direction in the ink jet method, andthe other is set as a sub scanning direction in the ink jet method; andthe ink jet head is set such that the intervals among lattice pointsalong the sub scanning direction is an integer multiple of effectiveintervals among ink expelling outlets of the ink jet head along the subscanning direction, when coating the droplets according to the dropletarrangement pattern.
 36. A nanoimprinting method as defined in claim 32,wherein: one of the A direction and the B direction is set as a mainscanning direction in the ink jet method, and the other is set as a subscanning direction in the ink jet method; and the ink jet head is setsuch that the intervals among lattice points along the sub scanningdirection is an integer multiple of effective intervals among inkexpelling outlets of the ink jet head along the sub scanning direction,when coating the droplets according to the droplet arrangement pattern.37. A nanoimprinting method as defined in claim 33, wherein: one of theA direction and the B direction is set as a main scanning direction inthe ink jet method, and the other is set as a sub scanning direction inthe ink jet method; and the ink jet head is set such that the intervalsamong lattice points along the sub scanning direction is an integermultiple of effective intervals among ink expelling outlets of the inkjet head along the sub scanning direction, when coating the dropletsaccording to the droplet arrangement pattern.
 38. A nanoimprintingmethod as defined in claim 34, wherein: one of the A direction and the Bdirection is set as a main scanning direction in the ink jet method, andthe other is set as a sub scanning direction in the ink jet method; andthe ink jet head is set such that the intervals among lattice pointsalong the sub scanning direction is an integer multiple of effectiveintervals among ink expelling outlets of the ink jet head along the subscanning direction, when coating the droplets according to the dropletarrangement pattern.
 39. A method for producing a droplet arrangementpattern, which is to be a reference for arranging droplets to beemployed in a nanoimprinting method comprising coating a first substratewith a plurality of droplets of resist material by the ink jet method,and pressing a linear pattern of protrusions and recesses of a mold ontothe surface of the first substrate which is coated with the droplets,comprising: coating a plurality of droplets of resist material at astandard amount onto a second substrate different from the firstsubstrate; pressing a second mold having a pattern of protrusions andrecesses, which is at least partially the same as the linear pattern ofprotrusions and recesses, against the surface of the second substratewhich is coated with the droplets, to spread the droplets to a degreethat the droplets contact each other; causing the shapes of the spreaddroplets of the standard amount to approximate ellipses; measuring thearrangement of the ellipses; rearranging the arrangements of themeasured ellipses such that the plurality of ellipses are closelypacked; and obtaining a droplet arrangement pattern constituted by aplurality of lattice points that correspond to positions at which theplurality of droplets are to be arranged, by designating the centers ofeach of the rearranged plurality of ellipses as lattice points.